56 lines
2.3 KiB
Diff
56 lines
2.3 KiB
Diff
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commit 9a0e174a39a3a65f628c6a55e29fe35f6d67bf42
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Author: Michael Jeanson <mjeanson@efficios.com>
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Date: Thu Nov 7 22:23:49 2024 +0100
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nptl: initialize rseq area prior to registration
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Per the rseq syscall documentation, 3 fields are required to be
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initialized by userspace prior to registration, they are 'cpu_id',
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'rseq_cs' and 'flags'. Since we have no guarantee that 'struct pthread'
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is cleared on all architectures, explicitly set those 3 fields prior to
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registration.
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Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
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Reviewed-by: Florian Weimer <fweimer@redhat.com>
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(cherry picked from commit 97f60abd25628425971f07e9b0e7f8eec0741235)
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diff --git a/nptl/descr.h b/nptl/descr.h
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index 4697f633e16c7359..a83df327e4bcba2e 100644
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--- a/nptl/descr.h
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+++ b/nptl/descr.h
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@@ -417,6 +417,8 @@ struct pthread
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{
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uint32_t cpu_id_start;
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uint32_t cpu_id;
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+ uint64_t rseq_cs;
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+ uint32_t flags;
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};
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char pad[32]; /* Original rseq area size. */
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} rseq_area __attribute__ ((aligned (32)));
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diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h
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index 7ea935b4adab8c20..37a8f630b6519ff0 100644
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--- a/sysdeps/unix/sysv/linux/rseq-internal.h
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+++ b/sysdeps/unix/sysv/linux/rseq-internal.h
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@@ -51,11 +51,21 @@ rseq_register_current_thread (struct pthread *self, bool do_rseq)
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/* The initial implementation used only 20 bytes out of 32,
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but still expected size 32. */
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size = RSEQ_AREA_SIZE_INITIAL;
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+
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+ /* Initialize the rseq fields that are read by the kernel on
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+ registration, there is no guarantee that struct pthread is
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+ cleared on all architectures. */
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+ THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_UNINITIALIZED);
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+ THREAD_SETMEM (self, rseq_area.rseq_cs, 0);
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+ THREAD_SETMEM (self, rseq_area.flags, 0);
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+
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int ret = INTERNAL_SYSCALL_CALL (rseq, &self->rseq_area,
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size, 0, RSEQ_SIG);
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if (!INTERNAL_SYSCALL_ERROR_P (ret))
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return true;
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}
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+ /* When rseq is disabled by tunables or the registration fails, inform
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+ userspace by setting 'cpu_id' to RSEQ_CPU_ID_REGISTRATION_FAILED. */
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THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
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return false;
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}
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